For noninvasive drug delivery and needle-free vaccinations, MIT researchers developed a way to use ultrasound waves to enhance the permeability of your skin to drugs.

Ultrasound waves can lightly wear away the top layer of skin, in a transient and pain-free way.

In the new work, the team found that applying two separate beams of ultrasound waves — one low frequency and one high frequency — can uniformly boost permeability across a region of skin more rapidly than using a single beam of ultrasound waves, according to the MIT News Office.

When ultrasound waves travel through a fluid, they create tiny bubbles that move chaotically. Once the bubbles reach a certain size, they become unstable and implode. Surrounding fluid rushes into the empty space, generating high-speed “microjets” of fluid that create microscopic abrasions on the skin. In this case, the fluid could be water or a liquid containing the drug to be delivered.

Combining high and low frequencies, they found, gave better results: the high-frequency ultrasound waves generate additional bubbles, which are popped by the low-frequency waves (pictured). The high-frequency ultrasound waves also keep the bubbles contained in the treatment area, creating more uniform abrasion.

They tested their new approach by delivering ultrasound waves to pig skin. When they applied either glucose or inulin (a carbohydrate) to the treated skin, they found that glucose was absorbed 10 times better, and inulin 4 times better when compared to a single-frequency system.

Here are some uses for such an ultrasound transdermal drug delivery system:

to deliver any type of drug or protein that’s currently given by capsule, potentially increasing the dosage that can be administered.

for topical drugs such as steroids like cortisol

drugs for skin conditions such as acne or psoriasis

to enhance the activity of transdermal patches already in use, such as nicotine patches

a noninvasive way for diabetics to control their blood sugar levels, through short- or long-term delivery of insulin.

to administer antigens for vaccines. This would be especially beneficial in developing countries, since the training required to administer such patches would be less intensive than that needed to give injections.

The team is working on a prototype for a handheld ultrasound device. The U.S. Food and Drug Administration has previously approved single-frequency ultrasound transdermal systems based on the work of MIT researchers Daniel Blankschtein and Robert Langer, so they’re hopeful that the improved system will also pass the safety tests.

Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York.
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